I. Field of the Invention
The present invention relates to an iron-tetraphenylporphine complex and, more particularly, to an iron-5,10,15,20-tetra(.alpha.,.alpha.,.alpha.,.alpha.-o-substituted phenyl)porphine complex having phosphocholine groups. The present invention also relates to a process for preparing the complex and an agent capable of adsorbing and desorbing oxygen containing the complex.
II. Description of the Prior Art
Many attempts have been made to prepare oxygen-adsorbing and desorbing agents using synthetic iron(II)-porphine complexes. One successful example is iron(II)-5,10,15,20-tetra(.alpha.,.alpha.,.alpha.,.alpha.-o-pivalamidophen yl)porphine complex reported by J. P. Collman et al., Journal of the American Chemical Society, 97, 1427 (1975). However, this complex can only function under limited conditions such as in anhydrous aprotic organic solvents or in a solid state, and it can not function under more general conditions such as in aqueous solvents. When industrial utilization such as oxygen enrichment, and utilizations in perfusion liquids for storing organs and as artificial blood used for living system as a useful oxygen-adsorbing and desorbing agent functioning under general conditions are considered, there is a strong demand for a material system which can adsorb and desorb oxygen effectively in water and, further, at room temperature or at a temperature of about 37.degree. C.
E. Hasegawa et al. have taught in their paper, Biochemical and Biophysical Research Communications, 105, 1416 (1982), to enclose an iron(II)-5,10,15,20-tetra(.alpha.,.alpha.,.alpha.,.alpha.-o-pivalamidophen yl)porphine complex in a liposome composed of a phospholipid. This complex is taken up in a hydrophobic region or liophilic layer of the liposome. It is reported that the complex, enclosed in a liposome, forms an oxygen complex stable at room temperature even if placed in water, and adsorbs and desorbs oxygen reversibly. Thus, to enclose a complex in a liposome is extremely effective in causing a complex to exhibit an adsobing and desorbing capability in water over a long period of time. It is to be noted, however, that the above-noted iron(II)-porphine complex is not easy to be solubilized in water because of its hydrophobic structure, and presents the difficulty that an amount of the complex to be embedded in a liposome of a given amount is small, resulting in that the adsorption and desorption capacity of the whole system is small.